I am a second year student at WesternU and rent really depends on how close you'd like to be to the school. Options putting you right on campus (like the Daumier or 777 apartments) may range in price from 1k$-1.5k; however, living in a home with other students or an apartment can range from 500$-1,000$ in adjacent neighborhoods. Most students live in Chino Hills (south of Pomona) or Claremont (north of Pomona), both friendly residential districts.
Pomona is an ideal location for a medical school since the city is medically underserved and allows students to make an impact in the community by volunteering their time in various student run clinics (Pomona Homeless Outreach Program, Pomona Community Health Action Team, amongst others).
Please feel free to message me if you have any questions whatsoever regarding WesternU, academics, extracurriculars, etc. I'd be glad to help!